Oil circuit breaker comprising an extinguishing chamber for high voltages



6 Jan. 19, 1965 PUCHE 3,166,659

W. R OIL CIRCUIT BREAKER COMPRISING AN EXTINGUISHING CHAMBER FOR HIGH VOLTAGES Filed Dec. 1. 1960 INVENTOR.

United States Patent Ofiice 3,166,659 Fatented Jan. 19, 1965 OIL CIRCUIT BREAKER COMPRISING AN EXTIN- GUISHING CHAMBER FOR HIGH VOLTAGES Walter Pucher, Ludvika, Sweden, assignor to Allrniinna Svenska Elektriska Aktieholaget, Vasteras, Sweden, a

Swedish corporation Filed Dec. 1, 1960, Ser. No. 73,129 Claims priority, application Sweden, Dec. 16, 1959, 11,851/59 3 Claims. (Cl. Mill-150) In oil circuit breakers an extinguishing chamber is known in which, at a breaking, the oil forced aside by the breaking gases during the first part of a breaking action increases the gas pressure in a closed space above the oil level in a pressure accumulating chamber arranged intheextinguishing chamber. At a certain distance between the contacts of the circuit breaker an outlet channel below the closed space is opened by the movable contact of the circuit breaker and the oil in the pres sure accumulating chamber is forced through the outlet channel by the gas pressure in the closed space in direction against the arc, as the breaking current approaches zero.

In extinguishing chambers of this type in which the arc is drawn through a fully closed extinguishing chamber it is necessary to hold the generated are energy low in order that the pressure in the extinguishing chamber shall not be too high. Consequently a long are of high current intensity cannot be allowed in the extinguishing chamber and because of this the distance between the stationary contact and the outlet slot has been chosen so that the are at high breaking current is extinguished the first time the breaking current approaches zero which may be only a small fraction of a cycle after the contacts are separated. At a high breaking voltage it may, however, happen that the arc is re-ignited by the recovery voltage due to the fact that the distance between the contacts hasnot yet been sufficiently large. The extinguishing chamber may in this case be exerted to such high pressures that it is damaged.

The present invention relates to an oil circuit breaker comprising an extinguishing chamber for high voltages in which chamber this disadvantage has been removed. In the extinguishing chamber an arc channel is arranged through which a movable contact is passed to a stationary contact, a pressure accumulating chamber partly filled with oil and comprising a gas filled closed space above the oil and an outlet channel which communicates with the pressure accumulating chamber. The outlet channel opens in the arc channel at a certain distance from the stationary contact and is opened at a breaking action by the movable contact. The invention is characterized in that the oil in the arc channel between the stationary contact and the outlet channel without generating a counter pressure can be freely forced aside by the breaking gases generated at a breaking action. This can be achieved by arranging for substantially free communication between the oil outside the extinguishing chamber and the space between the stationary contact and the outlet channel, as by pressure unloading channels through which said oil in the space can communicate with the oil outside the extinguishing chamber.

been separated) without the pressure in the extinguishing chamber increasing to an inadmissible value. Due to the breaking action being delayed until a breaking current passes through zero for the second or third time the risk of re-ignition of the arc will be very slight. For closing of the circuit breaker against a short circuit the invention has at high voltages a clear advantage in that the pressure in the extinguishing chamber is held within reasonable limits even if a long arc is generated between the contacts of the circuit breaker.

The extinguishing chamber may be provided with additional outlet channels which open in the arc channel and all communicate with the pressure accumulating chamber. This embodiment is especially suitable if a short circuit should occur while a breaking action was progressing. The chamber is then kept from exploding due to the fact that the gases around the are, as Well as through the pressure unloading channels, can expand through a plurality of outlet channels along the arc channel.

The extinguishing chamber may alternatively be provided with an outlet channel crossing the arc channel, through which outlet channel the arc channel communicates partly with the pressure accumulating chamber, partly with the space outside the extinguishing chamber.

The oil in the pressure accumulating chamber communicates with the oil outside the extinguishing chamber through an oil level channel and because of this the oil in the pressure accumulating chamber after a breaking action rises to the same level as before.

To reduce the strains in the pressure accumulating chamber at a breaking of large currents this chamber may be provided with extra outlet openings through which it communicates with the space outside the extinguishing chamber.

For low currents it may happen that the gas pressure in the pressure accumulating chamber will not be sufiiciently high for'the first breaking action to succeed. Because of this oil pockets may suitably be arranged around the arc channel on the other side of the outlet channel in relation to the stationary contact. In this way also extinguishing of small currents is made sure.

The accompanying drawings show three different embodiments of this invention. FIGURE 1 shows a longitudinal section of an extinguishing chamber with only one outlet channel .and FIGURE 2 an extinguishing chamber with a plurality of outlet channels from the pressure accumulating chamber to the arc channel. FIGURE 3 shows an extinguishing chamber for obtain ing a fiow of extinguishing medium straight across the arc channel.

In FIGURE 1, 1 designates an extinguishing chamber immersed in oil and 2 a pressure accumulating chamber filled with oil to a certain level and above the oil surface a gas-filled closed space 3. The stationary nozzle-formed contact 4 is arranged in the upper part of theextinguishing chamber. 5 is a movable contact and 6 an arc channel through which the movable contact may be passed to the stationary contact 4. 4 is an arcing space between the stationary contact and the opening of the arcing channel 6. The pressure accumulating chamber 2 communicates through the outlet channel 7 with the arc channel 6. The oil in the arcing space 4 is, through pressure unloading channels 8, in free communication with the oil outside the extinguishing chamber 1. The opening of the outlet channel 7 into the are channel 6 may be shaped like an annular slot which is arranged at such a distance from the stationary contact 4 that the outlet channel 7 is opened by the movable contact at least a halt period after the contacts have been separated. 9 is an oil level opening arranged in the pressure accumulating chamber in order that the oil in this after each breaking action shall rise to the same level as before the breaking action. To ensure the interruption of low current, oil pockets 10 have been arranged in the lower part of the extinguishing chamber. 11 are extra outlet openings for keeping the pressure in the extinguishing chamber within reasonable limits for high currents.

The circuit breaker in FIGURE 2 differs from the circuit breaker in FIGURE 1 only in that along the arcv channel a plurality of outlet channels 12 has been arranged, which outlet channels at a breaking are opened one after the other by the movable contact.

In FIGURE 3 the circuit breaker has been provided with outlet channels 13 which cross the arc channel 6. Thus, if the outlet channels 13 are followed in one direction, the arc channel communicates directly with the space outside the extinguishing chamber and in the oth er direction with the pressure accumulating chamber. In this embodiment the pressure in the arc channel. is always kept within reasonable values.

The circuit breaker functions in the following way: As the movable contact 5 leaves the stationary contact 4 an arc is generated which generates gas,thereby forcing aside the oil in arcing space 4 During the first part of the breaking action the oil forced aside will not cause any counter pressure as it can pass freely out to the oil outside the extinguishing chamber 1 through the channel 8. When, however, the outlet channel 7 is open the oil in this channel forced aside by the breaking gases will generate a high counter-pressure in the gas filled space 3. When the breaking current again approaches zero the pressure in the gases around the arc decreases and the oil in the pressure accumulating chamber is forced by the pressure in the space 3 in direction back against the arc. The extinguishing chamber in FIGURES 2 and 3 functions in, principally the same Way. The difference is that here the arc is exposed to a flow of oil and gas from a plurality of outlet channels.

I claim:

1. Oil circuit breaker comprising an extinguishing chamber for high voltages immersed in oil, means dividing said extinguishing chamber into at least one pressure accumulating chamber having a wall, and an arcing channel through said extinguishing chamber having openings at both ends, a stationary contact spaced at a distance from the arcing channel and a movable contact arranged to'pass into the arcing channel at the end remote from said stationary contact and to pass through the arcing channel and engage said stationary contact, the wall of said accumulating chamber having an oil-opening therein so positioned that said chamber is filled with oil only to a predetermined level, thus providing a gas-filled and closed space inside the accumulating chamber above said level, and a slot communicating with the oil space in the accumulator chamber opening into said arcing channel, said slot being uncovered by the movable contact during the opening movement of this contact, and means providing free and permanent comunication between the oil in the space between said stationary contact and said arcing channel with the oil surrounding the extinguishing chamber, whereby oil can be forced out of such space without substantial counterpressure by the gases generated at the beginning of the breaking movement, the slot being located at such a distance from the stationary contact that said slot is uncovered by the movable contact not earlier than half a current cycle after the contacts have been separated.

2. Oil circuit breaker according to claim 1 having in the wall of the arcing channel at least one additional slot in communication with the oil in the accumulating chamber.

slot in the wall of said arcing channel in communication with the oil outside the extinguishing chamber.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, ROBERT K. SCHAEFER, Examiners.

3. Oil circuit breaker according to claim 1, at least one 

1. OIL CIRCUIT BREAKER COMPRISING AN EXTINGUISHING CHANBER FOR HIGH VOLTAGES IMMERSED IN OIL, MEANS DIVIDING SAID EXTINGUSIHING CHAMBER INTO AT LEAST ONE PRESSURE ACCUMULATING CHAMBER HAVING A WALL, AND A ARCING CHANNEL THROUGH SAID EXTINGUISHING CHAMBER HAVING OPENINGS AT BOTH ENDS, A STATIONARY CONTACT SPACED AT A DISTANCE FROM THE ARCING CHANNEL AND A MOVABLE CONTACT ARRANGED TO PASS INTO THE ARCING CHANNEL AT THE END REMOTE FROM SAID STATIONARY CONTACT AND TO PASS THROUGH THE ARCING CHANNEL AND ENGAGE SAID STATIONARY CONTACT, THE WALL OF SAID ACCUMULATING CHAMBER HAVING AN OIL-OPENING THEREIN SO POSITIONED THAT SAID CHAMBER IS FILLED WITH OIL ONLY TO A PREDETERMINED LEVEL, THUS PROVIDING A GAS-FILLED AND CLOSED SPACE INSIDE THE ACCUMULATING CHAMBER ABOVE SAID LEVEL, AND A SLOT COMMUNICATING WITH OIL SPACE IN THE ACCUMULATOR CHAMBER OPENING INTO SAID ARCING CHANNEL, SAID SLOT BEING UNCOVERED BY THE MOVABLE CONTACT DURING THE OPENING MOVEMENT OF THIS CONTACT, AND MEANS PROVIDING FREE AND PERMANENT COMMUNICATION BETWEEN THE OIL IN THE SPACE BETWEEN SAID STATIONARY CONTACT AND SAID ARCING CHANNEL WITH THE OIL SURROUNDING THE EXTINGUISHING CHAMBER, WHEREBY OIL CAN BE FORCED OUT OF SUCH SPACE WITHOUT SUBSTANTIAL COUNTERPRESSURE BY THE GASES GENERATED AT THE BEGINNING OF THE BREAKING MOVEMENT, THE SLOT BEING LOCATED AT SUCH A DISTANCE FROM THE STATIONARY CONTACT THAT SAID SLOT SI UNCOVERED BY THE MOVABLE CONTACT NOT EARLIER THAN HALF A CURRENT CYCLE AFTER THE CONTACTS HAVE BEEN SEPARATED. 